The primary objective of the present workstatement is to develop a relatively rapid method for screening for agents which may be effective chemopreventive agents method for screening for agents which may be effective chemopreventive agents in the NMBA (Nitrosomethlybenzylamine) induced rat esophagus model. Rats will be treated weekly (for 3 weeks) with NMBA. Rats will then be kept for an additional 10 weeks. At that time animals will be sacrificed and the resulting esophageal slides examined by computer assisted morphologic analysis (nuclear characterization and ploidy) to determine the efficacy of the chemopreventive agents employed. A total of 8 different agents will be employed in this study. At lest two of these agents will have been previously examined i the complete 6 month esophageal study and thus serve as known controls for this revised assay. It is expected that this revised methodology may help to increase the sensitivity and decrease the assay time for examining for effective chemopreventive agents in this model.